JP4404862B2 - Preform for composite material and method for producing the same - Google Patents

Description

  The present invention relates to a composite preform for forming a metal composite by compounding with a light metal such as an aluminum alloy, and a method for producing the composite preform.

  For example, automobiles tend to have more parts manufactured from light metals such as aluminum, which are excellent in weight reduction, high durability, low thermal expansion, and the like, in order to improve fuel economy and driving performance. In particular, metal composites made by combining light metals and reinforcing materials such as ceramics are applied to those with severe usage environments such as engine parts, so that further weight reduction and high durability can be demonstrated. It has become.

  This metal composite material is obtained by molding a preform for a composite material having a predetermined shape with a reinforcing material such as ceramic fibers or ceramic particles in advance, and then impregnating the composite material preform with a melt of light metal by a die casting method or the like. It is formed. Here, the composite preform is formed by sintering ceramic fibers and / or ceramic particles at a predetermined temperature. In general, the ceramic fibers or / and ceramic particles are mixed with an inorganic binder such as alumina sol or silica sol in order to promote bonding of the fibers or / and particles before sintering. This inorganic binder binds together reinforcing materials such as ceramic fibers and ceramic particles by gelling and crystallizing during sintering.

By the way, the above-mentioned automobile engine parts are required to have improved wear resistance and vibration damping capability. Therefore, graphite, activated carbon, etc., which are excellent in lubricity and damping properties, are mixed and preformed for composite materials. A metal composite material has been proposed in which a preform is molded and the preform for the composite material is impregnated with a light metal such as an aluminum alloy (for example, Patent Document 1).
JP 2004-35910 A

  The metal composite material described above can exhibit high mechanical properties such as durability and strength when the molten metal of light metal spreads in the preform for composite material and is sufficiently impregnated. However, if the molten metal is not sufficiently impregnated into the composite preform, a relatively large nest (unimpregnated portion) is generated in the metal composite, and the metal composite exhibits its mechanical properties. It will not be able to fully demonstrate. For this reason, the preform for composite material is required to have excellent so-called air permeability so that the melt of light metal can easily flow inside and can be sufficiently impregnated. In particular, in a high-speed die casting method in which a molten metal is filled at a relatively high speed so that high productivity can be exhibited, a preform for composite material having high air permeability is essential.

  By the way, in the composite material preform having the above-described conventional configuration and mixing and sintering an inorganic binder such as alumina sol or silica sol, the alumina sol or silica sol is granular during sintering performed at 800 ° C. to 1500 ° C. It is crystallized to adhere to the surface of the reinforcing material such as ceramic fibers and ceramic particles, or the granular material is concentrated and solidified to adhere to the surface of the reinforcing material or between the reinforcing materials. Yes. For this reason, this composite preform has narrow gaps between the reinforcing materials, and the air permeability is generally hindered. When the preform for composite material having the conventional structure is impregnated with a molten metal of light metal, the molten metal cannot be sufficiently impregnated, and the above-described nest is generated in the metal composite material. Furthermore, when impregnated with a molten metal of light metal by the high-speed die casting method described above, there has been a problem that the preform for composite material is deformed and cracks such as cracks occur in the formed metal composite material. Such deformations and cracks are considered to be caused by insufficient strength of the composite preform, and bonding of reinforcing materials with an inorganic binder as described above is not suitable for high-speed die casting.

  In general, in the composite preform, the strength of the composite preform increases as the content of ceramic fibers and ceramic particles increases, but the air permeability tends to decrease. is there. Similarly, as the content is decreased, the air permeability is improved, but the strength is decreased. Thus, the preform for composite material cannot easily improve both strength and air permeability.

  The present invention has a high strength and excellent breathability, is applied to a high-speed die casting method, and can form a metal composite material that can exhibit excellent mechanical properties, and a method for producing the same Propose.

  The present invention relates to a composite preform formed by sintering ceramic fibers and / or ceramic particles, and forming a metal composite material by impregnating with a melt of light metal. And silica sol and calcium carbonate mixed with ceramic particles and sintered at a predetermined temperature, and the calcium-silicon produced by the reaction between the silica sol and calcium monoxide decomposed from calcium carbonate by the sintering Ceramic fibers or / and ceramic particles are bonded to each other by the sintered body, and voids are formed between the fibers or / and particles. Here, the calcium-silicon sintered body may be produced either as a crystallized compound or as a non-crystalline so-called glass state.

The preform for a composite material having such a structure, in which ceramic fibers or / and ceramic particles are bonded to each other by a calcium-silicon sintered body, is obtained by crystallizing the inorganic binder in a granular shape or a lump shape as described above. Compared with a preform formed by bonding ceramic fibers or / and ceramic particles, high strength can be exhibited. This is because the calcium-silicon sintered body produced by the reaction of silica sol (SiO ₂ ) and calcium monoxide (CaO) decomposed from calcium carbonate (CaCO ₃ ) is compared with the inorganic binder of the conventional structure. This is because the ceramic fibers and / or ceramic particles can be firmly bonded.

  Furthermore, in the preform for composite material of the present invention, ceramic fibers or / and ceramic particles are bonded to each other by a calcium-silicon sintered body (Ca-Si sintered body), and between the fibers or particles. A void is formed. Here, since the calcium-silicon sintered body (Ca-Si sintered body) is produced so as to adhere to the ceramic fibers or / and ceramic particles in a film form, the voids are formed relatively wide. It becomes. On the other hand, in the conventional structure in which the inorganic binder is crystallized as described above, this granular or massive crystal is attached to the surface of the ceramic fiber or / and ceramic particles, or between the fibers or / and particles. Adhere to. From this, the gap formed in the preform for composite material of the present invention can be secured wider than the gap existing in the preform having the conventional configuration. Therefore, the composite preform according to the present invention can exhibit excellent air permeability.

  Thus, since the composite preform of the present invention can exhibit both high strength and excellent air permeability, even when impregnated with a light metal melt by a high-speed die casting method, the melt should be sufficiently impregnated. It does not cause deformation and cracks. Thus, the preform for composite material of the present invention can be applied to high-speed die casting which can exhibit high productivity, and a metal composite material having excellent mechanical properties can be obtained.

  In the composite preform described above, the silica sol mixed with the ceramic fibers or / and the ceramic particles has a silica weight of 0.01 or more with respect to the total weight of the ceramic fibers and the ceramic particles. The weight ratio is 0.15 or less, and the calcium carbonate mixed with the ceramic fibers or / and ceramic particles has a weight of 0.001 or more with respect to the total weight of the ceramic fibers and ceramic particles. In addition, a configuration is proposed in which the weight ratio is 0.15 or less. Here, when the ceramic particles are not mixed, the weight of the ceramic fibers becomes this total weight, and when the ceramic fibers are not mixed, the weight of the ceramic particles becomes the total weight.

In such a configuration, by a calcium-silicon sintered body (Ca-Si sintered body) generated from silica sol (SiO ₂ ) and calcium monoxide (CaO) decomposed from calcium carbonate (CaCO ₃ ), Ceramic fibers or / and ceramic particles can be sufficiently firmly bonded to each other, and a sufficiently wide void can be formed between the fibers or / and particles. Here, as the amount of calcium-silicon sintered body (Ca-Si sintered body) generated with respect to ceramic fibers and ceramic particles increases, the amount of adhesion to the fibers or / and particles also increases. Or / and the space | gap produced | generated between particle | grains becomes narrow, and the air permeability tends to reduce generally. On the other hand, as the generation amount of the calcium-silicon sintered body (Ca-Si sintered body) decreases, the strength of bonding the ceramic fibers and / or ceramic particles to each other decreases, and the strength of the composite preform decreases. Show the trend. Therefore, the calcium-silicon sintered body is sintered at the time of sintering by setting each weight ratio of mixing silica sol and calcium carbonate to the respective weight ratios with respect to the total weight of the ceramic fibers and ceramic particles as in this configuration. An appropriate amount of (Ca-Si sintered body) is produced, and this preform for composite material can exhibit high strength and excellent air permeability in a balanced and stable manner.

  In the silica sol, it is preferable that the silica contained therein has a weight ratio of 0.04 or more and 0.10 or less with respect to the total weight of the ceramic fibers and ceramic particles. Similarly, calcium carbonate having a weight ratio of 0.04 or more and 0.10 or less with respect to the total weight is preferable. By such a calcium-silicon sintered body (Ca-Si sintered body) generated from calcium carbonate and silica sol at various weight ratios, the preform for composite material has an even better balance between strength and air permeability. Can be a thing.

In the above-described composite preform, a configuration is proposed in which the calcium carbonate mixed with the silica sol in the ceramic fibers and / or ceramic particles has a particle size of 10 μm or less. Here, calcium carbonate (CaCO ₃ ) having a particle diameter of 0.1 μm or more, which can be handled relatively easily and can be generally generated, can be suitably used.

Calcium monoxide that reacts with silica sol (SiO ₂ ) by sintering tends to decrease in reactivity with the silica sol as its shape increases. Then, by mixing calcium carbonate having a particle size of 10 μm or less, calcium monoxide and silica sol react sufficiently and easily, and the calcium-silicon sintered body (Ca-Si sintered body) becomes a ceramic fiber or / and ceramic. It becomes easy to produce | generate to particle | grains in the smooth film form. Thereby, the space | gap between ceramic fiber or / and a ceramic particle will be ensured enough and appropriately, and this preform for composite materials can exhibit the further outstanding air permeability. Furthermore, a calcium-silicon sintered body (Ca-Si sintered body) produced by a sufficient reaction between calcium monoxide and silica sol bonds ceramic fibers or / and ceramic particles more firmly to each other. This composite preform can exhibit even higher strength. As the calcium carbonate, those having a particle size of 0.1 μm or more and 5 μm or less can be suitably used because they exhibit higher reactivity.

  In the composite preform described above, a configuration is proposed in which aluminum borate particles having a particle size of 10 μm or less are used as ceramic particles before sintering. Here, as the aluminum borate particles, particles having a particle diameter of 0.1 μm or more that can be handled relatively easily and can be generally generated can be suitably used.

Here, when mixed particle size 10μm or less of aluminum borate particles _{(9Al 2 O 3 · 2B 2} O 3), by sintering, and the aluminum borate particles, silica sol (SiO _2), calcium carbonate (CaCO ₃ ) Decomposed from calcium monoxide (CaO) to produce a calcium-boron-silicon sintered body (Ca-B-Si sintered body). The calcium-boron-silicon sintered body (Ca-B-Si sintered body) forms a composite preform having a structure in which ceramic fibers and / or other ceramic particles are bonded to each other. This calcium-boron-silicon sintered body (Ca-B-Si sintered body), like the above-mentioned calcium-silicon sintered body (Ca-Si sintered body), strengthens ceramic fibers and / or ceramic particles. And a relatively wide space is formed by adhering to the fibers or / and particles in a film form. Therefore, the preform for composite material of this configuration exhibits high strength and has excellent air permeability as compared with the preform of the conventional configuration described above. The preform for composite material of this configuration can be applied to a high-speed die casting method, and can form a metal composite material that can exhibit excellent mechanical properties.

Here, the aluminum borate particles show a tendency that the reactivity of silica sol (SiO ₂ ) and calcium monoxide (CaO) decreases as the particle size increases. Therefore, in this configuration, the particle size is set so that a calcium-boron-silicon sintered body (Ca-B-Si sintered body) capable of firmly bonding ceramic fibers and / or ceramic particles can be generated sufficiently and easily. Aluminum borate particles of 10 μm or less are mixed. As for the aluminum borate particles, particles having a particle size of 1 μm or more and 5 μm or less are more excellent in reactivity between silica sol (SiO ₂ ) and calcium monoxide (CaO), and can be used more suitably.

  On the other hand, as a manufacturing method for forming the above preform for composite material, the present invention includes a mixing step of preparing a mixed aqueous solution by mixing silica sol and calcium carbonate in water with ceramic fibers or / and ceramic particles, and the mixed aqueous solution. A dehydration step of removing water from the mixture to form a mixture, and sintering the mixture at a predetermined temperature, thereby reacting the silica sol with calcium monoxide decomposed from calcium carbonate to cause a calcium-silicon sintered body And a sintering step in which ceramic fibers or / and ceramic particles are bonded to each other by the calcium-silicon sintered body.

Here, in the sintering step, calcium monoxide (CaO) is decomposed from calcium carbonate (CaCO ₃ ), and this calcium monoxide (CaO) and silica sol (SiO ₂ ) are reacted to produce a calcium-silicon sintered body ( Ca-Si sintered body) is generated. The calcium-silicon sintered body (Ca-Si sintered body) bonds ceramic fibers and / or ceramic particles to each other. The composite preform produced in this way can exhibit higher strength than the preform bonded with the inorganic binder having the conventional structure described above. As described above, this calcium-silicon sintered body (Ca-Si sintered body) has a stronger binding force than that obtained by crystallizing and binding an inorganic binder such as alumina sol or silica sol. Therefore, the composite preform produced by this method has high strength.

  Further, since the calcium-silicon sintered body (Ca-Si sintered body) is produced by adhering to the ceramic fibers or / and ceramic particles in a film shape, a relatively wide gap is formed between the fibers or / and particles. Is generated. Since the voids are sufficiently wide as compared to the gaps between the fibers and / or particles formed by crystallizing and sintering the inorganic binder in the conventional configuration described above, the composite material block produced by this method is used. The reform has excellent breathability.

  In the mixing step, ceramic fibers or / and ceramic particles, silica sol, and calcium carbonate are stirred in water. Therefore, the mixture before the sintering step includes these fibers or / and particles, silica sol, and calcium carbonate. Are distributed almost uniformly throughout. As a result, in the sintering process, the above-mentioned calcium-silicon sintered body (Ca-Si sintered body) is generated almost uniformly throughout, and the ceramic fibers and / or ceramic particles are bonded almost uniformly throughout. Will be. Therefore, the preform for composite material produced by this method has almost no uneven distribution of strength and air permeability, and can generally exhibit high strength and excellent air permeability.

  According to this manufacturing method, the composite preform having excellent strength and air permeability described above can be manufactured relatively easily and stably. The composite material preform can be applied to a high-speed die casting method, and can form a metal composite material that can exhibit high mechanical properties.

  As a method for producing the preform for composite material, the silica sol mixed in the mixing step has a weight ratio of 0.01 or more and 0.15 or less with respect to the total weight of the silica and ceramic particles. In addition, the calcium carbonate mixed in the mixing step has a weight ratio of 0.001 or more and 0.15 or less with respect to the total weight of the ceramic fibers and ceramic particles. A method is proposed. Here, when the ceramic particles are not mixed, the weight of the ceramic fibers becomes the total weight, and when the ceramic fibers are not mixed, the weight of the ceramic particles becomes the total weight.

The mixed aqueous solution prepared in the mixing step is sintered in the sintering step through the dehydration step, so that the ceramic fiber or the calcium-silicon sintered body (Ca-Si sintered body) generated in the sintering step is used. It is possible to bond the ceramic particles sufficiently firmly to each other and form a sufficiently wide void between the fibers or / and the particles. Here, if the silica sol (SiO ₂ ) and calcium carbonate (CaCO ₃ ) mixed in the mixing step are larger than the weight ratio with respect to the total weight of the ceramic fibers and ceramic particles described above, a calcium-silicon sintered body (Ca-Si) The amount of (sintered body) produced is increased, and the amount of adhesion to the ceramic fibers and / or ceramic particles is also increased. And the space | gap produced | generated between ceramic fiber or / and a ceramic particle becomes narrow, and the air permeability of the preform for composite materials shows the tendency to reduce. On the other hand, if the silica sol (SiO ₂ ) and calcium carbonate (CaCO ₃ ) are less than the above weight ratio to the total weight, the amount of calcium-silicon sintered body (Ca-Si sintered body) generated is reduced. Moreover, the force which mutually bonds a ceramic fiber or / and ceramic particle | grains also becomes weak, and the tendency for the intensity | strength of the preform for composite materials to fall is shown. From the above, by setting the mixing amount of silica sol (SiO ₂ ) and calcium carbonate (CaCO ₃ ) to the above-described weight ratio, a composite material that can exhibit high strength and excellent air permeability in a well-balanced manner. Reform can be manufactured stably.

  The weight of silica contained in the silica sol mixed in the mixing step is preferably 0.04 or more and 0.10 or less with respect to the total weight of the ceramic fibers and ceramic particles. The weight of calcium carbonate is preferably set to a weight ratio of 0.04 or more and 0.10 or less with respect to the total weight. Thereby, it is possible to manufacture a preform for a composite material that is further excellent in the balance between high strength and excellent air permeability.

  In the composite material preform manufacturing method described above, a method is proposed in which the calcium carbonate mixed in the mixing step has a particle size of 10 μm or less.

In the sintering process, calcium monoxide (CaO) that reacts with silica sol (SiO ₂ ) tends to become less reactive with the silica sol as its shape increases. For this reason, by mixing calcium carbonate having a particle size of 10 μm or less in the mixing step, calcium monoxide and silica sol react sufficiently and easily in the sintering step, so that a calcium-silicon sintered body (Ca-Si) is obtained. (Sintered body) may be produced in a state of being attached to the ceramic fiber or / and ceramic particles in a smooth film state. Thereby, the space | gap between ceramic fiber or / and ceramic particle | grains will be ensured sufficiently and appropriately, and the preform for composite materials which exhibits the further outstanding air permeability can be manufactured. In addition, relatively small calcium carbonate having a particle size of 10 μm or less is easily dispersed in the mixing step, and is present more uniformly in the mixed aqueous solution. For this reason, the calcium-silicon sintered body (Ca-Si sintered body) produced in the firing step adheres more uniformly over almost the entire ceramic fiber or ceramic particle.

  Therefore, the composite preform produced by the present method can exhibit high strength and excellent air permeability evenly as a whole, and can be excellent in stability and balance.

  Note that calcium carbonate having a particle size of 0.1 μm or more can be used because it is easy to handle and can be generated relatively easily. And in order to improve the reactivity with a silica sol, a thing with a particle size of 0.1 micrometer or more and 5 micrometers or less can be used conveniently.

  Moreover, in the above-described composite material preform, a mixed aqueous solution is prepared by mixing aluminum borate particles having a particle size of 10 μm or less as ceramic particles in the mixing step.

In the mixing step, by mixing the particle size 10μm or less of aluminum borate particles _{(9Al 2 O 3 · 2B 2} O 3), the sintering process, calcium monoxide separated from the calcium carbonate (CaCO ₃₎ (CaO) Reacts with silica sol (SiO ₂ ) and the aluminum borate particles to produce a calcium-boron-silicon sintered body (Ca-B-Si sintered body). The calcium-boron-silicon sintered body (Ca-B-Si sintered body) firmly bonds ceramic fibers or / and other ceramic particles to each other, and is sufficient between the fibers or / and particles. A wide space is formed. Here, the aluminum borate particles _{(9Al 2 O 3 · 2B 2} O 3) shows in accordance with the particle size decreases, calcium monoxide and (CaO) silica sol tends to be good reactivity with (SiO ₂₎ . For this reason, by using aluminum borate particles having a particle size of 10 μm or less, a calcium-boron-silicon sintered body (Ca-B-Si sintered body) capable of firmly bonding ceramic fibers and ceramic particles in the sintering step. ) Can be generated sufficiently and easily.

  Therefore, according to this method, a preform for composite material that can exhibit high strength and excellent air permeability can be manufactured. Then, by applying the composite preform produced by this method to the high-speed die casting method, a metal composite material that can exhibit excellent mechanical properties can be formed.

Incidentally, aluminum borate particles _{(9Al 2 O 3 · 2B 2} O 3) mixed in the mixing step, the following particle size 1μm or more and 5μm is, the reaction of calcium monoxide and (CaO) and silica sol (SiO ₂₎ It is more excellent in properties and can be suitably used.

  In the present invention, as described above, the ceramic fiber or / and ceramic particles are mixed with silica sol and calcium carbonate and sintered at a predetermined temperature, and the sintered silica sol and calcium carbonate are decomposed by the sintering. A composite material composite in which ceramic fibers or / and ceramic particles are bonded to each other and voids are formed between the fibers or / and particles by a calcium-silicon sintered body produced by a reaction with calcium oxide. Since it is a reform, it can exhibit high strength and excellent air permeability as compared with the preform bonded by crystallization of the inorganic binder having the conventional structure described above. The preform for composite material can be applied to a high-speed die casting method capable of exhibiting high productivity, and can form a metal composite material having excellent mechanical properties.

  Here, the silica sol mixed with the ceramic fibers or / and the ceramic particles has a weight ratio of 0.01 to 0.15 with respect to the total weight of the ceramic fibers and the ceramic particles. The calcium carbonate mixed with the ceramic fibers and / or ceramic particles has a weight ratio of 0.001 or more and 0.15 or less with respect to the total weight of the ceramic fibers and ceramic particles. In the configuration as described above, high strength and excellent air permeability can be exhibited in a balanced and stable manner.

  Further, when the calcium carbonate mixed with the ceramic fiber or / and the ceramic particles has a particle size of 10 μm or less, the calcium monoxide decomposed from the calcium carbonate easily reacts with the silica sol, and the calcium-silicon firing Since the bonded body adheres to the fibers or / and particles in a smooth film shape, higher strength and excellent air permeability can be exhibited.

  In addition, when the ceramic particles before sintering were composed of aluminum borate particles having a particle size of 10 μm or less, the aluminum borate particles, silica sol, and calcium carbonate were decomposed. Ceramic fibers or / and ceramic particles are bonded by a calcium-boron-silicon sintered body produced by reaction with calcium monoxide. Even in the preform for composite material, it is possible to exhibit high strength and excellent air permeability as compared with the preform having the above-described conventional configuration.

  On the other hand, as a manufacturing method of the above-mentioned composite preform, a mixing step of mixing a silica fiber and / or ceramic particles with silica sol and calcium carbonate in water to prepare a mixed aqueous solution, and removing water from the mixed aqueous solution Each ceramic fiber or each of the ceramic fibers or the dehydration step for forming a mixture and the calcium-silicon sintered body produced by reacting the silica sol with calcium monoxide decomposed from calcium carbonate by sintering the mixture at a predetermined temperature. And / or a sintering process in which ceramic particles are bonded to each other, so that the above-described composite preform having high strength and excellent air permeability can be manufactured relatively easily and stably. You can get. Furthermore, the composite preform produced by this production method can be applied to a high-speed die casting method, and can exhibit a high productivity and obtain a metal composite material having excellent mechanical properties.

  Here, the silica sol to be mixed in the mixing step is such that the weight of silica contained in the silica sol becomes a weight ratio of 0.01 or more and 0.15 or less with respect to the total weight of the ceramic fibers and ceramic particles. In addition, the calcium carbonate to be mixed in the mixing step is high in the method in which the weight is 0.001 or more and 0.15 or less with respect to the total weight of the ceramic fibers and ceramic particles. It is possible to produce a preform for composite material that can exhibit strength and excellent air permeability in a balanced and stable manner.

  Further, in the method in which the calcium carbonate to be mixed in the mixing step has a particle size of 10 μm or less, calcium monoxide decomposed from calcium carbonate easily reacts with silica sol, and the calcium-silicon sintered body is Smoothly adheres to the fibers or / and particles. Thus, the composite preform produced by this method can exhibit high strength and excellent breathability in a more balanced and stable manner.

  Further, in the mixing step, the aluminum borate particles having a particle size of 10 μm or less are mixed as ceramic particles to prepare a mixed aqueous solution. In the sintering step, the aluminum borate particles are mixed with silica sol. It reacts with calcium monoxide decomposed from calcium carbonate to produce a calcium-boron-silicon sintered body. The preform for composite material in which fibers or particles are bonded by this calcium-boron-silicon sintered body can exhibit high strength and excellent air permeability as compared with the preform having the above-described conventional configuration.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a process of manufacturing a composite preform 1, and the preform manufacturing process includes a mixing process, a dehydrating process, a drying process, and a sintering process. FIG. 1A shows a mixing step, in which a mixed aqueous solution 8 is prepared by stirring each material in water with a stirring bar 31 in a predetermined container 21 and mixing them almost uniformly. Then, the mixed aqueous solution 8 is transferred from the container 21 to the suction molding device 22. FIG. 1B shows a dehydration step, in which water is sucked from the mixed aqueous solution 8 through the filter 24 by the vacuum pump 23 to obtain the mixture 9. And the drying process which takes out this mixture 9 from the suction molding machine 22 and fully dries is performed (illustration omitted). FIG. 1C shows a sintering process. The mixture 9 is placed on a table 32 in the heating furnace 25, and the inside of the heating furnace 25 is evacuated by a vacuum pump 29 connected to the heating furnace 25. Then, the desired composite preform 1 is obtained by heating and sintering in a predetermined atmosphere.

  Next, the metal composite material 10 is formed by impregnating the above-mentioned composite material preform 1 with the molten aluminum alloy 6 in a die casting process as shown in FIG. In the die casting apparatus 33 that performs this die casting process, as shown in FIG. 2A, a mold 34 that forms a cavity 35 having a predetermined shape and a molten metal 6 that is injected into the cavity 35 are temporarily retained. And a sleeve 37 for injecting the molten metal 6 by a plunger tip 38 that is controlled to advance and retreat. Then, the composite preform 1 is disposed in the cavity 35 of the mold 34, and the molten metal 6 injected into the cavity 35 is injected into the sleeve 37 with the plunger tip 38 in the retracted position. As shown in FIG. 2B, the sleeve 37 is connected to the gate 36 of the mold 34 and the plunger chip 38 is driven to advance, whereby the molten metal 6 in the sleeve 37 is injected into the cavity 35. In this way, the metal composite material 10 is obtained. The die casting apparatus 33 can change the driving speed for driving the plunger tip 38 to advance, and can perform so-called high speed die casting by making the driving speed relatively high.

  Manufacturing process of the above-described composite material preform 1, die casting process of impregnating the composite material preform 1 with molten aluminum alloy 6, composite material preform 1 and metal composite formed by each process, respectively. The material 10 is demonstrated according to the following specific examples.

In the mixing step (FIG. 1A) described above, the following materials (i) to (v) below are put into the water in the container 21.
(I) Alumina short fiber 2 (average fiber diameter 5 μm, average bulk ratio 20 cc / 5 gf)
(Ii) Aluminum borate particles 3 (9Al ₂ O ₃ .2B ₂ O ₃ , average particle size 30 μm)
(Iii) Calcium carbonate particles 4 (CaCO ₃ , average particle diameter 0.3 μm)
(Iv) Graphite particles 5 (average particle size 20 μm)
(V) Silica sol 7 (SiO ₂ , colloidal aqueous solution with a concentration of about 40%)
Here, the average fiber diameter, the average bulk ratio, and the average particle diameter are average values of the fiber diameter, the bulk ratio, and the particle diameter, respectively, and have variations. The short alumina fibers 2 are ceramic fibers according to the present invention, and the aluminum borate particles 3 and the graphite particles 5 are ceramic particles according to the present invention. These ceramic fibers and ceramic particles are so-called reinforcing materials.

  Here, the alumina short fibers 2 were adjusted to be about 10% by volume, the aluminum borate particles 3 to be about 8% by volume, and the graphite particles 5 to be about 6% by volume. Further, the calcium carbonate particles 4 are added so that the weight is about 0.05 with respect to the total weight of the aluminum short fibers 2, the aluminum borate particles 3 and the graphite particles 5. 7 was added so that the weight of silica in the aqueous solution was about 0.06 with respect to the total weight.

  Then, by stirring the aqueous solution containing the materials (i) to (v) with the stirring rod 31, a mixed aqueous solution 8 in which the materials are mixed almost uniformly is obtained. In addition, the dispersibility of the calcium carbonate 4 having a small particle diameter is good, and it exists over almost the entire region of the mixed aqueous solution 8.

  Next, the mixed aqueous solution 8 is transferred to the suction molder 22 and the above-described dehydration step (FIG. 1B) is performed. The suction molder 22 is provided with a cylindrical aqueous solution retaining part 26 into which the mixed aqueous solution 8 flows into an upper region 26a, and a lower part of the aqueous solution retaining part 26. A water retention portion 27 that communicates with the lower region 26b of the aqueous solution retention portion 26, and a vacuum pump 23 that is connected to the water retention portion 27 and sucks moisture from the aqueous solution retention portion 26 via the water retention portion 27. ing.

  In the dehydration step, after the mixed aqueous solution 8 has flowed into the upper region 26a of the aqueous solution retaining portion 26 of the suction molder 22, the vacuum pump 23 is operated, so that the water in the mixed aqueous solution 8 is converted into water. Suction is performed from the retention portion 27 through the lower region 26 b of the aqueous solution retention portion 26. Thereby, the water | moisture content of the mixed aqueous solution 8 flows down through the filter 24, and the cylindrical mixture 9 formed by mixing each above-mentioned material is obtained. Further, the mixture 9 is taken out from the suction molder 22 and placed in a drying furnace or the like at about 120 ° C., and a drying process is performed to sufficiently remove moisture (not shown).

  Here, since the mixture 9 after the dehydration step is composed of the mixed aqueous solution 8 in which the respective materials are dispersed almost uniformly in the mixing step, similarly, the respective materials are almost uniformly dispersed. It has become. In this mixture 9, the silica sol 7 is attached in a film shape on the surfaces of the short alumina fibers 2, the aluminum borate particles 3, and the graphite particles 5, and the calcium carbonate particles 4 are substantially uniform over the entire area of the silica sol 7. (Not shown). The adjacent alumina short fibers 2, aluminum borate particles 3, and graphite particles 5 are in a state of being bonded by the adhesive force of the silica sol 7 (not shown). Thereby, at the time of conveyance to the next heating furnace 25, the mixture 9 is prevented from being deformed or broken, and the form of the mixture 9 can be maintained. The state in which the reinforcing materials are bonded to each other by the adhesive force of the silica sol 7 is weaker than the bonding after the sintering process described later, and can withstand relatively careful conveyance.

  Next, the process proceeds to the above-described sintering step (FIG. 1C). The mixture 9 is placed on a table 32 installed in the heating furnace 25. And the vacuum pump 29 is operated and the inside of the heating furnace 25 is made into a 10 Pa vacuum state. Thereafter, the furnace is heated while flowing nitrogen gas at a constant flow rate of 5 L / min and maintained at about 1150 ° C. Then, the furnace is cooled to room temperature (not shown) to obtain a cylindrical composite preform 1A (see FIG. 3). Here, in Example 1, since the graphite particles 5 are mixed, the firing step is performed in a nitrogen gas atmosphere so that the graphite particles 5 are not oxidized and lost.

In this firing step, the calcium carbonate particles (CaCO ₃ ) 4 attached to the silica sol 7 are decomposed into calcium monoxide (CaO) and carbon dioxide (CO ₂ ) at a high temperature, and this calcium monoxide (CaO) is By reacting with silica sol (SiO ₂ ) 7 (not shown), a calcium-silicon sintered body (Ca-Si sintered body) 11 in a glass state is generated (see FIGS. 3 and 4). Here, as described above, the silica sol 7 is in the form of the mixture 9 and adhered to the surfaces of the alumina short fibers 2, the aluminum borate particles 3, and the graphite particles 5, and the calcium carbonate particles 4. Are dispersed almost uniformly and adhered to the silica sol 7. Thereby, a film-like calcium-silicon sintered body 11 can be generated almost uniformly on the alumina short fibers 2, the aluminum borate particles 3 and the graphite particles 5 (see FIG. 4). And the calcium-silicon sintered compact produced | generated in this way couple | bonds the reinforcing material of the alumina short fiber 2, the aluminum borate particle 3, and the graphite particle 5 firmly. Thus, the composite preform 1A formed in this sintering step can exhibit high strength.

  In the composite preform 1A, the calcium-silicon sintered body (Ca-Si sintered body) 11 covers the alumina short fibers 2, the aluminum borate particles 3, and the graphite particles 5 from the enlarged photograph of FIG. Thus, it can adhere to the smooth film | membrane form, and it can confirm that the adjacent reinforcing materials are couple | bonded by this calcium-silicon sintered compact 11 (refer FIG. 4). In addition, since the calcium-silicon sintered body 11 is attached in a film shape so as to cover the alumina short fibers 2, the aluminum borate particles 3 and the graphite particles 5, it is relatively wide between these reinforcing materials. A void 14 is formed. Thereby, this preform 1A for composite materials can exhibit excellent air permeability.

  Thus, the composite preform 1A is substantially uniformly distributed throughout the entire length of the alumina short fiber 2, the aluminum borate particles 3, and the graphite particles 5 in a film shape. Is attached. Therefore, the above-described strength and air permeability can be exhibited almost uniformly throughout the entire area, and overall high strength and excellent air permeability can be stably exhibited.

  In addition, the preform manufacturing process which manufactures the preform 1 for composite materials in this way is comprised according to the manufacturing method of the preform for composite materials concerning this invention.

  Next, the composite preform 1A manufactured in the above-described preform manufacturing process is combined with an aluminum alloy by the die casting apparatus 33 (see FIG. 2) to form a desired metal composite 10A. In this die casting apparatus 33, the composite preform 1A is impregnated with a molten metal 6 of an aluminum alloy (JIS ADC12). Here, in the first embodiment, the mold 34 is formed by fitting the convex upper mold 34a and the concave lower mold 34b to form the cylindrical cavity 35. In the cavity 35, the composite preform 1A formed in a cylindrical shape can be fitted. The lower die 34b of the die 34 is connected to a connecting portion (not shown) to which the sleep 37 is connected, and when the sleep 37 is connected, the molten metal 6 in the sleep 37 flows into the cavity 35. A gate 36 is provided. When the upper mold 34a and the lower mold 34b are fitted together, a water passage 39 that communicates the cavity 35 and the gate 36 is also formed, and the molten metal 6 that flows from the gate 36 flows into the water path. It flows into the cavity 35 through 39.

  First, the above-mentioned composite preform 1A is preheated at about 600 ° C., and the mold 34 is kept at 200 to 250 ° C. Then, as shown in FIG. 2A, the preheated composite material preform 1A is disposed on the lower mold 34b, and the upper mold 34a is fitted together. Thereby, the composite preform 1 </ b> A is accommodated in the cylindrical cavity 35 of the mold 34. On the other hand, the molten aluminum alloy 6 maintained at about 680 ° C. is poured into the sleeve 37 at the lower position of the mold 34 and the plunger tip 38 in the retracted position (not shown). Thereafter, as shown in FIG. 2 (B), the sleep 37 is moved upward to connect the upper end of the sleeve 37 to the gate 36 of the mold 34. Then, the plunger tip 38 is driven to advance from the retracted position at a predetermined driving speed, and the molten metal 6 in the sleep 37 is injected into the cavity 35. Here, the driving speed of the plunger tip 38 is adjusted so that the injection speed of the molten metal 6 flowing from the gate 36 becomes a relatively high speed of about 2.0 m / s.

  Then, as shown in FIG. 2C, when the molten metal 6 is filled in the cavity 35, the plunger tip 38 stops and the injection of the molten metal 6 stops, and after cooling, the sleeve 37 is moved down to mold the mold. Remove from 34. Then, the upper mold 34a and the lower mold 34b of the mold 34 are separated, and the metal composite material 10A (see FIG. 5) is taken out from the mold 34 (FIG. 2D). In addition, after removing this metal composite material 10A from the metal mold | die 34, the site | part formed with the gate 36 and the water channel 39 is removed, and it has a cylindrical shape (illustration omitted). This metal composite material 10A is formed by impregnating a composite preform 1A with an aluminum alloy 6 '(see FIG. 5) and is formed into a cylindrical shape in this embodiment. . As a result of cross-sectional observation of the metal composite material 10A, as shown in FIG. 5, the aluminum alloy 6 ′ is sufficiently impregnated between the alumina short fibers 2, the aluminum borate particles 3 and the graphite particles 5, and the nest (unimpregnated) It was confirmed that no part) occurred.

  Further, as described above, even when the molten aluminum alloy 6 is injected at a relatively high speed, the composite preform 1A is not deformed or broken, and cracks or cracks occur in the formed metal composite 10A. Absent. This also shows that the composite preform 1 of Example 1 has high strength and excellent air permeability.

On the other hand, Example 2 is the mixing process of the preform manufacturing process (FIG. 1A), and the following materials (i) to (v) below are put into the water in the container 21.
(I) Alumina short fiber 2 (average fiber diameter 5 μm, average bulk ratio 20 cc / 5 gf)
(Ii) Aluminum borate particles 3 (9Al ₂ O ₃ .2B ₂ O ₃ , average particle size 3 μm)
(Iii) Calcium carbonate particles 4 (CaCO ₃ , average particle diameter 0.3 μm)
(Iv) Graphite particles 5 (average particle size 20 μm)
(V) Silica sol 7 (SiO ₂ , colloidal aqueous solution with a concentration of about 40%)
Here, the aluminum borate particles are the same as those in Example 1 except that the average particle diameter is 3 μm. The mixing amount of the aluminum borate particles is the same as that of the aluminum borate particles 3 in Example 1. Hereinafter, the description of the same steps and configurations as in Example 1 will be omitted as appropriate, and the same configurations will be denoted by the same reference numerals.

  Water is removed from the mixed aqueous solution 8 obtained from this mixing step by the suction molder 22 in the dehydration step (FIG. 1B) to obtain a mixture 9. After this mixture 9 is dried in a drying process (not shown), the process proceeds to the sintering process. In the sintering step (FIG. 1 (C)), heating in a nitrogen gas atmosphere and holding at about 1150 ° C., followed by furnace cooling, yielding a composite preform 1B (see FIG. 6).

In the sintering process of Example 2, the calcium carbonate particles (CaCO ₃ ) 4 are decomposed into calcium monoxide (CaO) and carbon dioxide (CO ₂ ) at a high temperature, and the calcium monoxide (CaO) and silica sol _(SiO 2) 7 and the aluminum borate particles _{by (9Al 2 O 3 · 2B 2} O 3) and reacts, calcium glassy state - boron - silicon sinter (Ca-B-Si sinter) 12 is generated (see FIG. 6). The calcium-boron-silicon sintered body 12 is attached in a smooth film shape over almost the entire area so as to cover the surfaces of the short alumina fibers 2 and the graphite particles 5, and these reinforcing materials are attached to each other. Bond firmly. This is also clear from the enlarged photograph of the composite preform 1B shown in FIG. Furthermore, since this composite preform 1B is also adhered smoothly so that the calcium-boron-silicon sintered body 12 covers the surface of the reinforcing material, as in Example 1 described above, A relatively wide space 14 is formed between the materials, and has excellent air permeability.

  Next, as shown in FIG. 2, the composite preform 1B is impregnated with the molten aluminum 6 (JIS ADC12) 6 by the die casting apparatus 33 described above to form the metal composite 10B (see FIG. 7). To do. Even in the die-casting process by the die-casting apparatus 33, the desired metal composite material 10B is obtained by executing in the same manner as in the first embodiment. Even in the composite material preform 1B of the second embodiment, even if the molten metal 6 is impregnated at a relatively high injection speed (about 2.0 m / s) as in the above-described first embodiment, The desired metal composite material 10B was obtained without causing breakage, cracking, cracking, or the like. From this, it is clear that the preform 1B for composite material has high strength and excellent air permeability. Further, as a result of cross-sectional observation of the metal composite material 10B, as shown in FIG. 6, the aluminum alloy 6 ′ is sufficiently impregnated between the alumina short fibers 2 and the graphite particles 5, and a nest (unimpregnated portion) is generated. Confirmed not.

<Comparative Example 1>
Further, as Comparative Example 1, a preform 61 for a composite material having a conventional configuration was manufactured in which silica sol 7 was mixed as an inorganic binder without mixing calcium carbonate particles 4.
This composite preform 61 is manufactured in the same preform manufacturing process as in the first embodiment. In the mixing step (see FIG. 1A), the following materials (i) to (iv) below are stirred in water in the container 21 to obtain a mixed aqueous solution (not shown).
(I) Alumina short fiber 2 (average fiber diameter 5 μm, average bulk ratio 20 cc / 5 gf)
(Ii) Aluminum borate particles 3 (9Al ₂ O ₃ .2B ₂ O ₃ , average particle size 30 μm)
(Iii) Graphite particles 5 (average particle size 20 μm)
(Iv) Silica sol 7 (SiO ₂ , colloidal aqueous solution having a concentration of about 40%)
Here, Comparative Example 1 is the same as Example 1 except that the calcium carbonate particles 4 are not mixed. Therefore, hereinafter, the description of the same steps and configurations as those of the first embodiment will be omitted as appropriate, and the same configurations are denoted by the same reference numerals.

  After the above-described mixing step, similarly to Example 1, a dehydration step, a drying step, and a sintering step are sequentially performed (see FIG. 1) to obtain a composite preform 61 (see FIG. 8). As shown in the enlarged photograph of FIG. 8, the composite material preform 61 is composed of the alumina 62, the aluminum borate particles 3, and the graphite particles 5. Are attached so as to protrude outward (see FIG. 9). Further, in part, the crystallized granular material 62 of the silica sol 7 is solidified and present as a lump. The silica sol 7 thus crystallized bonds the adjacent reinforcing materials together.

  From the enlarged photograph (FIG. 8) of the composite preform 61 described above, it can be easily inferred that the gap between the reinforcing materials is narrower than in the first and second embodiments.

  The composite material preform 61 is impregnated with the molten aluminum alloy 6 by the above-described die casting apparatus 33 (see FIG. 2) to obtain a metal composite material 60 (see FIG. 10). Here, when the plunger tip 38 is driven to advance so as to achieve the same injection speed (about 2.0 m / s) as in the first embodiment, the composite preform 61 is deformed, and proper molding is performed. I couldn't. For this reason, the injection speed of the molten metal 6 was gradually reduced, and molding was performed at an injection speed at which the composite material preform 61 was not deformed or cracked or cracked after forming. The injection speed was about 1.0 m / s. Therefore, the composite material preform 61 of Comparative Example 1 must be impregnated with the molten metal 6 at a relatively low speed, and the strength and air permeability thereof are the composite material preforms 1A and 1B of Examples 1 and 2 described above. It is inferred that it is lower than

  As a result of cross-sectional observation of the metal composite material 60 formed as described above, it was confirmed that a nest (unimpregnated portion) X was present as shown in FIG. Therefore, it is surmised that this metal composite 60 cannot sufficiently exhibit mechanical properties as compared with the metal composites 10A and 10B of Examples 1 and 2 described above.

  Next, tests for evaluating the strength and air permeability of the composite material preforms 1A and 1B of Example 1 and Example 2 described above and the composite material preform 61 of Comparative Example 1 were performed. Furthermore, a test for evaluating mechanical properties of the metal composites 10A and 10B of Example 1 and Example 2 and the metal composite 60 of Comparative Example 1 was performed. The mechanical characteristics are typically evaluated by evaluating the hardness.

  Here, in Examples 1 and 2 and Comparative Example 1 described above, the composite material preforms 1A, 1B, and 61 are manufactured in a cylindrical shape having an outer diameter of 100 mm, an inner diameter of 90 mm, and a height of 120 mm. The metal composite materials 10A, 10B, and 60 are formed in substantially the same size and shape according to the composite material preforms 1A, 1B, and 61.

  As a strength evaluation test of the composite preforms 1A, 1B, 61, a compression test was performed in which the cylindrical shape was compressed in the radial direction, the respective maximum loads were obtained, and this was evaluated as strength. As a result, as shown in FIG. 11, the composite material preform 61 of Comparative Example 1 was about 10 N, whereas the composite material preforms 1A and 1B of Examples 1 and 2 were both about 20N. This proved that the composite preforms 1A and 1B have high strength.

  In addition, as a breathability evaluation test for the composite preforms 1A, 1B, 61, air of a predetermined pressure is blown from one end face of the cylindrical shape, and the pressure of air blown from the other end face is measured. Loss was determined and evaluated as breathability. That is, the air permeability is improved as the pressure loss is reduced. This breathability evaluation test is conducted in accordance with JIS R2115 “Testing method for breathability of refractory bricks”. As shown in FIG. 11, the pressure loss of the composite preform 61 of Comparative Example 1 was about 7.0 KPa, whereas the pressure of the composite preform 1A of Example 1 was as shown in FIG. The loss was about 5.0 KPa, and the pressure loss of the composite preform 1B of Example 2 was about 5.5 KPa. Thereby, it was proved that the preforms 1A and 1B for composite materials have excellent air permeability.

  Furthermore, a Vickers hardness test was performed as a hardness evaluation test for evaluating each hardness of the metal composite materials 10A, 10B, and 60. In accordance with JIS Z 2244, this Vickers hardness test was performed by pressing a predetermined quadrangular pyramid indenter against the surface of the aluminum composite layer 12 of each composite material with a load of 98 N, and measuring the hardness. As a result, the hardness of the metal composite material 61 of Comparative Example 1 was 110 Hv, whereas the metal composite material 10A of Example 1 was 125 Hv, and the metal composite material 10B of Example 2 was 135 Hv. . Thereby, it was proved that the metal composites 10A and 10B have high hardness.

  Furthermore, when a test for evaluating the durability of each of the metal composite materials 10A, 10B, 60 was performed, the metal composite materials 10A, 10B of Example 1 and Example 2 were compared with the metal composite material 60 of Comparative Example 1. And showed high durability. Such durability evaluation results and the above-described hardness evaluation results are also clear from the fact that the metal composites 10A and 10B are sufficiently impregnated with the aluminum alloy 6 ', and almost no nests are formed. (See FIGS. 4 and 6). Therefore, the metal composite materials 10A and 10B according to the present invention have high mechanical properties excellent in the durability and the above-described hardness as compared with the metal composite material 60 having the conventional configuration.

  From such evaluation results, in the present invention, it is possible to obtain composite preforms 1A and 1B having both high strength and excellent air permeability as compared with preform 61 of the conventional configuration. it can. Furthermore, the composite preforms 1A and 1B according to the present invention can be applied to a high-speed die casting method in which the molten aluminum alloy 6 is filled at a relatively high speed. Almost no impregnation site) is generated. The metal composites 10A and 10B have excellent mechanical properties (hardness and durability). Thus, according to the composite preform and the method for manufacturing the same according to the present invention, it can be used for parts having strict required performance such as automobile engine parts. Furthermore, since it can be applied to a high-speed die casting method, the productivity of such composite parts can be improved and high market competitiveness can be exhibited.

  In Examples 1 and 2 described above, the short alumina fibers 2 are used as the ceramic fibers, and the graphite particles 5 and the aluminum borate particles 3 are used as the ceramic particles. A structure using aluminum oxide whisker and potassium titanate whisker is also possible. Moreover, it is good also as a structure which mixes only any one of a ceramic fiber and a ceramic particle, and even if it is in this structure, it is possible to exhibit the effect similar to Example 1, 2 mentioned above. Furthermore, the graphite particles 5 may not be mixed, or activated carbon may be mixed instead of the graphite particles 5. When this graphite particle or activated carbon is mixed, wear resistance and vibration damping performance are improved, which is suitable for engine parts and the like. Further, when graphite particles and activated carbon are not used, it is not necessary to prevent these oxidation disappearances, so the sintering step may be performed in the air.

  The shape dimensions of the reinforcing material such as the alumina short fibers 2, the aluminum borate particles 3 and the graphite particles 5 are, for example, the alumina short fibers 2 having an average diameter of 1 μm to 10 μm and an average bulk ratio of 10 cc / 5 gf to 50 cc. Even when a material of / 5 gf is used, it is possible to manufacture the composite preform 1 that can exhibit the same effects as described above. Similarly, aluminum borate particles 3 having an average particle diameter of 1 μm to 100 μm and graphite particles 5 having an average particle diameter of 1 μm to 1000 μm can be used. In addition, when different types of ceramic fibers and ceramic particles are used, those having substantially the same shape and dimensions can be suitably used.

  Moreover, in the manufacturing process of the composite preform 1 described above, the temperature at which the sintering process is performed may be 800 ° C. to 1500 ° C. depending on various conditions. For example, a promoter for promoting the sintering reaction may be newly mixed and performed at a relatively low temperature. In Examples 1 and 2 described above, it is preferable to carry out at 1000 ° C. to 1200 ° C.

  In addition, in the manufacturing process of the composite material preform 1 of Example 1 described above, a calcium-silicon sintered body (Ca-Si sintered body) 11 in an amorphous state is generated. The calcium-boron-silicon sintered body (Ca-B-Si sintered body) 12 in a glass state is generated. Depending on the mixing amount in the mixing step and the firing conditions in the firing step, these sintered bodies may be It may be produced as a crystalline compound. And even if these sintered compacts are produced | generated as a compound, the effect similar to the above can be exhibited appropriately.

  In this invention, it is not limited to the Example mentioned above, About another structure, it can change suitably within the range of the meaning of this invention.

It is explanatory drawing showing the preform manufacturing process which manufactures the preform 1 for composite materials concerning this invention. It is explanatory drawing showing the die-cast shaping | molding process which shape | molds the metal composite material 10 from the preform 1 for composite materials manufactured at the preform manufacturing process same as the above. It is (A) enlarged photograph and (B) enlarged photograph which expanded further partially of preform 1A for composite materials of Example 1. FIG. It is the schematic diagram which expanded the preform 1A for composite materials same as the above. It is a cross-sectional enlarged photograph of 10 A of metal composite materials shape | molded from the preform 1A for composite materials same as the above. It is (A) enlarged photograph and (B) the enlarged photograph which expanded further partially of preform 1B for composite materials of Example 5. FIG. It is a cross-sectional enlarged photograph of the metal composite material 10B shape | molded from the preform 1B for composite materials same as the above. It is (A) enlarged photograph and (B) the enlarged photograph which expanded further partially of the preform 61 for composite materials of the comparative example 1. FIG. It is the schematic diagram which expanded the preform 61 for composite materials same as the above. It is a cross-sectional enlarged photograph of the metal composite material 60 shape | molded from the preform 61 for composite materials same as the above. It is an evaluation result figure showing the result of having evaluated the intensity | strength and air permeability of each preform 1A, 1B, 61 for composite materials of Examples 1, 2 and Comparative Example 1. FIG.

Explanation of symbols

1, 1A, 1B Preform for composite material 2 Alumina short fiber (ceramic fiber)
3 Aluminum borate particles (ceramic particles)
4 Calcium carbonate particles 6 Molten aluminum alloy 7 Silica sol 8 Mixed aqueous solution 9 Mixture 10, 10A, 10B Metal composite 11 Calcium-silicon sintered body (Ca-Si sintered body)
12 Calcium-boron-silicon sintered body (Ca-B-Si sintered body)
14 Air gap

Claims (6)

In a preform for a composite material, which is formed by sintering ceramic fibers or / and ceramic particles and is formed by impregnating a molten metal of light metal,
The total weight of silica sol and ceramic fibers and ceramic particles containing silica in a weight ratio of 0.01 to 0.15 with respect to the total weight of the ceramic fibers and ceramic particles in the ceramic fibers or / and ceramic particles Is mixed with calcium carbonate having a weight ratio of 0.001 or more and 0.15 or less, and sintered at a predetermined temperature, and is decomposed from silica sol and calcium carbonate by the sintering. A ceramic fiber or / and ceramic particles are bonded to each other and a void is formed between the fibers or / and particles by a calcium-silicon sintered body produced by a reaction with calcium oxide. Preform for composite materials. The composite preform according to claim 1, wherein the calcium carbonate mixed with the silica sol in the ceramic fibers or / and the ceramic particles has a particle diameter of 10 μm or less. The preform for composite material according to claim 1 or 2 , wherein aluminum borate particles having a particle size of 10 µm or less are used as ceramic particles before sintering. In a method for producing a composite preform for sintering a ceramic fiber or / and ceramic particles and impregnating a molten metal of light metal after the sintering to form a metal composite material,
The total weight of silica sol and ceramic fibers and ceramic particles containing silica in a weight ratio of 0.01 to 0.15 with respect to the total weight of the ceramic fibers and ceramic particles in the ceramic fibers or / and ceramic particles Mixing step of preparing a mixed aqueous solution by mixing calcium carbonate having a weight ratio of 0.001 or more and 0.15 or less in water with water,
A dehydration step of removing water from the mixed aqueous solution to form a mixture;
By sintering this mixture at a predetermined temperature, the silica sol and calcium monoxide decomposed from calcium carbonate are reacted to form a calcium-silicon sintered body, and the calcium-silicon sintered body produces ceramic fibers or And / or a sintering step in which ceramic particles are bonded to each other. The method for producing a preform for composite material according to claim 4, wherein the calcium carbonate mixed in the mixing step has a particle size of 10 µm or less. The method for producing a composite preform according to claim 4 or 5 , wherein in the mixing step, aluminum borate particles having a particle size of 10 µm or less are mixed as ceramic particles to prepare a mixed aqueous solution.